CVE-2026-53095bpf: Fix abuse of kprobe_write_ctx via freplace

Official description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix abuse of kprobe_write_ctx via freplace uprobe programs are allowed to modify struct pt_regs. Since the actual program type of uprobe is KPROBE, it can be abused to modify struct pt_regs via kprobe+freplace when the kprobe attaches to kernel functions. For example, SEC("?kprobe") int kprobe(struct pt_regs *regs) { return 0; } SEC("?freplace") int freplace_kprobe(struct pt_regs *regs) { regs->di = 0; return 0; } freplace_kprobe prog will attach to kprobe prog. kprobe prog will attach to a kernel function. Without this patch, when the kernel function runs, its first arg will always be set as 0 via the freplace_kprobe prog. To fix the abuse of kprobe_write_ctx=true via kprobe+freplace, disallow attaching freplace programs on kprobe programs with different kprobe_write_ctx values.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/b312cf41b9e43f442613053f6cad39898e1baf96
• https://git.kernel.org/stable/c/9836cadbd96c7e0dbb0018fa60e7872dd31ac4f8
• https://git.kernel.org/stable/c/611fe4b79af72d00d80f2223354284447daafae9